Close encounter of a hovering "gun metal gray, metallic platform"

This incident happened decades ago, so I am not sure if you would have any interest; however, here it is anyway:
In 1969, the weekend before Labor Day (at around 8:30 PM), I was with my friend "Butch" on the Garden State Parkway (driving north near the Raritan exit). We were heading home from the New Jersey Shore, when I noticed something odd. Between two electrical towers, to my right, was something that ....at first... looked like an extension of the towers. Passing by, I told Butch to turnaround and come back to the sighting to get a better look. We did so after going about 1/3 mile up the road. To our amazement, we arrived at the site and witnessed a huge, silent, hovering "platform" .... for lack of a better description. Leaving the car, we approached the object at a clearing where it was lingering about 75-100 feet above the ground. We could see it was in the somewhat shape of a triangle/trapezoid with red, green, amber and white lights around its perimeter. It was about 150 feet across, 10 feet in height. It had a cross beam supporting structure (similar to what you see on a bridge). An opaque dome was atop with an antenna-like appendage protruding from the dome. Standing underneath it, we could see a formation/series of "pipes". In the center was a concave, circular indentation. The sun had just gone down and suddenly the object cast a milky, white light from its indentation to the ground, lighting up the area underneath. Just then we noticed several cars had parked along the highway. A man came to where we stood. He asked me what the thing was. I said I did not know. The three of us were stunned as I commented that it was so close, I could hit it with a rock (which I did not of course). After a few minutes, Butch and I decided to report it to the N.J. State Police, a few miles north up the road. When we got to the police station, we told the officer what we saw. He said that they had already dispatched a patrol car to the incident (obviously they had already received similar reports). We left the station. Returning to the site, the craft was gone. The man who came up to us said that it slowly departed.... heading east towards the ocean. Butch and I decided to drive back home, not saying a word until we arrived at our destinations. Anecdotally, I learned some weeks later that there was a Naval Research Center not far from the incident. COMMENTARY: I never felt that this was extraterrestrial, rather that it was man-made.... considering the object appeared to be made of prosaic parts... gun metal gray in color, metallic in composition, having rivets, a cross beam supporting structure and "piping" underneath (that looked similar to that of the A/C cooling found in a refrigerator). If anyone has information relating to this Close Encounter, please contact me, as this has confounded me to this day. What I have described is real, not a dream, blimp, drone, hallucination or flight of fancy. I am now 75 years old and would love an explanation after all these years. THANK YOU.